If you split the wooden top, and hinge it to the sides, it'll be able to swing out to the sides. or you can extend pins on the sides and drill the top to hang on the sides... I'll be building this... when I have the money for materials :-) !

because the swirl flaps , even if you just remove the flap itself, will eventually start leaking oil from the crank case ventilators. One idea/thought of the cause of this initial failure of oil leaking is, the EGR soot wears away at the seals. So if 'that' theory is correct, if you block the EGR or disabling of the EGR duty cycle via tuning(expensive but easy) , you may never need to delete the swirl flaps.